Choosing the best epoxy coating for your storage tanks takes time and effort.
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To speed up the selection process and ensure you make the right choice, below, the Industrial Inspection & Consulting team weighs the pros and cons of solvent-based, water-based, and 100% solids epoxies.
Facts About Solvent-Based Epoxy Coatings: The Classic Choice
Solvent-based epoxies have been around since the mid-20th century. They use organic solvents to dissolve epoxy resins and hardeners before application. Once applied, the solvents evaporate, leaving behind a durable, cross-linked epoxy coating.
Solvent-based epoxies have excellent adhesion and chemical resistance. They can withstand exposure to hydrocarbons, acids, and alkalis. Formulations with high solids content also have abrasion and impact resistance. &#; Not NSF Approved for Potable Water
Will it meet your requirements?
For industrial storage tanks subject to harsh conditions, solvent-based epoxy is a good choice. However, the organic solvents present safety hazards and necessitate special handling. They require adequate ventilation, emit a strong odor during application, and release volatile organic compounds (VOCs) during curing. These factors can pose environmental concerns. This epoxy coating also requires more rigorous surface preparation for proper adhesion.
Facts About Water-Based Epoxy Coatings: A Safer Alternative
Water-based epoxy is a balanced choice: They provide exceptional performance while reducing environmental impact.
Many water-based epoxies contain little to no volatile organic compounds, which makes them an environmentally friendly option compared to solvent-based epoxies. They produce minimal hazardous air pollutants and have a nearly non-existent smell. &#; Not used in Potable Water or Industrial Coatings
Will it meet your requirements?
In terms of performance, water-based epoxy coatings provide excellent adhesion and durability. They are highly resistant to abrasions, stains, and various substances stored in tanks, including oils, gasoline, acids, and other chemicals.
As for the downsides, water-based epoxies typically require more coats to achieve an equivalent dry film thickness as solvent-based coatings. They have smaller application windows, slower cure times, and less tolerance for surface moisture during application.
Facts About 100% Solids Epoxy Coatings: The Most Durable Choice
Solids epoxy coatings provide superior protection for storage tanks. They contain zero VOCs or solvents, resulting in a highly durable, chemical-resistant finish.
Will it meet your requirements?
100% solids epoxy coatings have a high volume of epoxy resins and hardeners, guaranteeing a tough coating. Plus, without solvents, there is no evaporation. This eliminates the risk of coating thickness reduction.
These coatings meet NSF 600 regulations for potable water tank linings, meaning they are ideal for tanks storing consumables (e.g., drinking water and food). The dense, cross-linked structure of 100% solids epoxy coatings blocks the ingress of moisture and chemicals, preventing contamination.
Now, you might be wondering, are there any disadvantages? In truth, the one minor &#;con&#; is that 100% solids are more difficult to apply than solvent-based and water-based alternatives. They have a short pot life of only 30 minutes, so they must be applied promptly after mixing the resin and hardener. The coating&#;s high viscosity also requires more advanced spray equipment for precise application.
If you want to learn more, please visit our website Epoxy coated tanks.
Solvent-Based vs. Water-Based vs. 100% Solids Epoxy: Which Should You Choose?
Are you still undecided? Let the Industrial Inspection Group help you make the right choice. To identify the appropriate epoxy for your coatings project, our meticulous process involves an on-site assessment of your tanks and a comprehensive analysis of their intended uses. Get in touch with us today to request a quote. With the right epoxy and independent coating inspectors by your side, your tanks will remain in service for decades to come.
About the author:
Arianna Berry is a freelance writer for Water & Wastes Digest. Berry can be reached at [ protected] or 904.451..
Water and wastewater each have unique struggles that people can address by applying protective coatings. This protection is especially important to wastewater disposal and treatment structures prone to environmental challenges, such as wetting-drying cycles, microbiologically-induced chemicals, cavitation, solid particle friction, carbonation and periods of freezing and thawing.
It can take days for wastewater to get to a plant, and during that time, microorganisms wreak havoc on substrates. For example, anaerobic sulfate-reducing bacteria (SRB) digest solid wastes, deposit polythionates and other sulfates onto the concrete and release carbonic acid (H2CO3) into the air above.
Virgin concrete&#;s alkaline chemistry then reacts with the carbonic acid to dramatically lower the concrete&#;s pH, which creates an optimal environment for &#;concrete devouring&#; bacteria in the head space above the wastewater. As a result, sulfur-oxidizing bacteria (SOB) Thiobacillus (among others) speed concrete corrosion by producing hydrogen sulfide (H2S) gas that combines with water to form strongly corrosive sulfuric acid (H2SO4). This microbiologically influenced corrosion (MIC) of concrete and metal surfaces causes billions of dollars worth of water and sewer system damage in the U.S. annually.
Protective coatings are often applied to concrete and metal components to mitigate this costly degradation. However, they only offer adequate substrate protection so long as they remain intact and must be applied flawlessly with no blisters, bugholes, honeycombs, pores, pinholes or punctures.
While coatings are typically epoxy-, polyurethane- or polyurea-based, some promising new hybrids are on the market.
The Most Common Coating Materials
Epoxy Coatings. Epoxies (typically high solids, amine-cured) are commonly used in damp environments such as wet wells, maintenance holes and clarifiers. These acid-resistant coatings are typically high build and offer long-lasting moisture and vapor corrosion protection by preventing water penetration. Epoxies can also be formulated to be used in water applications certified to ANSI 61 potable water.
As a rule of thumb, unless applying a cement-epoxy mortar, wait 28 days (as per SSPC&#;s SP 13) before applying an epoxy coating to new concrete. This waiting period allows the concrete to hydrate, to allow the moisture content to drop to less than 4%, and is vital to ensure the tenacious mechanical bond that epoxy coatings take about four to five hours to develop.
Polyurethane Coatings. Polyurethanes are typically high solids, high build, aromatic and two-component. They resist high acid concentrations and are unique in that they can be either flexible or rigid. They allow for fast return to service and require as little as 30 minutes for a solid cure. However, the higher moisture vapor transmission rate can translate to a weaker bond.
Spray-applied Polyurea Coatings. Like Polyurethanes, spray-applied polyureas are organic polymers, allow for a fast return to service, are flexible and allow for structural movement. However, they may allow for more moisture vapor transmission and are not as effective for full immersion for clarifier components. They cure so rapidly that they may not adequately wet the concrete to develop the needed adhesion for a strong bond. In addition, some formulations cannot withstand hydrolysis and dissolve in water.
In , Tripp Ishmael of Raven Lining Systems (acquired by PPG in February ) developed AquataFlex, a novolac epoxy-polyurethane hybrid that combines the chemical resistance of epoxy and the buildability of polyurethane with the flexibility of polyurea. AquataFlex products provide high-performance protection across a wide range of temperatures and humidities, are 100% solids with zero VOCs and are ANSI 61 certified for potable water use. In addition, they are certifiably bio-based and deliver strong adhesion properties to properly prepared concrete, steel, aluminum, wood and composites.
The company is the world’s best Wastewater Treatment Tanks supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.
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